1. Field of the Invention
The present invention relates to an image pickup apparatus having a lens array, and an image pickup optical system.
2. Description of the Related Art
Recently, it has been proposed for image pickup apparatus to perform calculations using data obtained by an image pickup element and to perform digital image processing in accordance with the data to output various kinds of images. A “Plenoptic 2.0 Camera” that simultaneously obtains a two-dimensional light intensity distribution and parallax information on an object plane (collectively, “light field”) using “Light Field Photography” is disclosed in the literature, Todor Georgiev, et al., “Full Resolution Light Field Rendering”, Adobe Technical Report January 2008, and Todor Georgiev, et al., “Superresolution with Plenoptic 2.0 Camera”, 2009 Optical Society of America. According to such image pickup apparatuses, a focus position of an image, a depth of field, or the like can be changed by obtaining a light field and then performing image processing after taking the image.
However, the image pickup apparatus needs to use a pixel of the image pickup element for storing the parallax information in addition to storing the two-dimensional light intensity distribution. Therefore, spatial resolution deteriorates compared to an image pickup apparatus that stores only the two-dimensional light intensity distribution. A configuration in which a certain point on an image plane formed by a main lens unit is imaged at a different pixel position by each lens (sometimes referred to as a “micro-lens”) of a lens array is disclosed in the literature, Todor Georgiev, et al., “Superresolution with Plenoptic 2.0 Camera”, 2009 Optical Society of America. A plurality of small images obtained in this way are reconstructed to obtain a high-resolution reconstructed image. This method of obtaining a high-resolution image is referred to as a “pixel shift effect”.
However, the specific configuration that is needed in order to obtain high resolution is not disclosed in the literature, Todor Georgiev, et al., “Superresolution with Plenoptic 2.0 Camera”, 2009 Optical Society of America.